Virtual network provisioning over flexible optical transport infrastructure

Current transport network owners are focused on offering services on top of the infrastructures they own, while end users have no control over them. Traditionally, this has been their business model, as the cost of building the infrastructures to provide services is considerably high. However, the traffic on Internet has been, and still is, rapidly increasing over the years. Additionally new emerging services are pushing the limits of existing telecommunication infrastructures, particularly transport optical networks. To overcome such situation, network virtualization has been considered as an effective solution for the future optical networks architectures. Thanks to Virtual Optical Networks (VONs), it is possible to create mission-specific logic infrastructures, which fulfil the exact requirements of the applications that will run on top of them, sharing a unique physical substrate. However, the applicability of virtualization techniques to the optical domain is still under research, being on key point the mapping of the virtual resources to the actual physical ones. However, virtualization per se does not provide a solution flexible enough in terms of bandwidth utilization. For this to happen, an equally flexible transport technology must be adopted. Elastic Optical Networks (EONs) have been presented as an efficient solution for flexible bandwidth allocation. Additionally, due to the dinamicity of the traffic patterns that such virtual networks will face, it is highly desirable to provide a physical substrate that will help on keeping the associated operational expenditures (OPEX) at low levels, being a very important parameter the energy consumption. The energy consumption topic has been subject of big research efforts in order to provide more energy efficient optical transport networks, which, at their turn, will help on the creation of less costly virtual infrastructures. This thesis is devoted to the study of resource allocation to VONs, aiming to provide a flexible, efficient and optimized environment for the embedding of the VONs to the actual physical substrate. The considered scenario is composed of an underlying optical transport network and multiple client VONs that have to be allocated on top. In such scenario, a key aspect relates to how actual resources are associated to the virtual ones, guaranteeing the isolation among VONs and satisfying the resources requirements of every one of them. After an introduction to the thesis, chapter 2 surveys nowadays optical network infrastructures, concluding on the need to move towards a more dynamic and efficient optical network infrastructure. Next, it proceeds to summarize the state of the art of the concepts that enable for such network architecture, namely, VONs, EONs and energy efficient optical infrastructures. Then, chapters 3, 4 and 5 focus on providing solutions to optimize specific aspects of these enabling concepts. More in details, chapter 3 studies the main challenges on the VON embedding problem and presents solutions that allow for an optimized resoure assignment to VONs in a physical substrate depending on the VONs characteristics and the sppecific network substrate. Chapter 4 proposes the Split Spectrum (SS) approach as a way to improve the spectrum utilization of EONs. Finally, chapter 5 focuses on provide and evaluate routing and architectural solutions in aims to reduce the energy consumption of the optical substrate so as VONs with lower OPEX can be deployed on top of it.Els actuals propietaris de xarxes de transport es centren en oferir serveis mitjançant les infraestructures que posseeixen, mentre els usuaris finals no tenen cap control sobre aquests. Tradicionalment, aquest ha estat el seu model de negoci, ja que el cost de construir aquestes infraestructures és considerablement elevat. Tanmateix, el tràfic a Internet ha estat creixent de manera ràpida durant els últims anys. A més, l'aparició de nous serveis està portant al límit les actuals infraestructures de telecomunicacions, especialment les xarxes òptiques de transport. Per tal de superar aquesta situació, la virtualització de xarxes és considerada com una solució efectiva per les futures arquitectures de xarxes òptiques. Gràcies a les Xarxes Òptiques Virtuals (VONs), és possible crear infraestructures lògiques específiques en la seva missió, les quals permeten satisfer els requisits de les aplicacions que s'executaran a través d'elles, compartint un únic substrat físic. Tanmateix, l'aplicació de les tècniques de virtualització en el domini òptic encara és subjecte d'investigació, sent el mapeig entre els recursos virtuals i els recursos físics un punt clau que cal adreçar. No obstant això, la virtualització en si mateixa no proporciona una solució prou flexible en termes d'utilització de l'espectre. Per aquest motiu és necessari que el substrat físic adopti una tecnologia igualment flexible. Les Xarxes Òptiques Elàstiques (EONs) es presenten com una solució eficient per a una assignació flexible de l'espectre. A més, a causa del dinamisme dels perfils de trafic als quals s'enfrontaran les VONs, és desitjable proporcionar una infraestructura física que ajudi a mantenir baixes les despeses operatives (OPEX) d'aquestes xarxes, sent un paràmetre molt important el consum energètic. El tema del consum energètic ha estat subjecte de grans iniciatives de recerca per tal de proporcionar xarxes de transport òptiques més eficients energèticament, les quals permetran crear VONs menys costoses. Aquesta tesi està dedicada a l'estudi l'assignació de recursos a les VONs, amb l'objectiu de proporcionar un entorn flexible, eficient i optimitzat per a la incrustació de les VONs al substrat físic. L'escenari considerat es compon d'una xarxa de transport subjacent i múltiples VONs client a col·locar sobre el substrat físic. En aquest escenari, un aspecte clau es refereix a com els recursos reals s'associen als virtuals, garantint l'aïllament entre VONs i satisfent els recursos demanats per cada una d'elles. Després d'una introducció a la tesi, el capítol 2 revisa les infraestructures de xarxa òptica actuals, concloent en la necessitat d'avançar cap a infraestructures més dinàmiques i eficients. Tot seguit, es procedeix a resumir l'estat de l'art dels conceptes que habilitaran aquesta arquitectura de xarxa, bàsicament, VONs, EONs i les xarxes òptiques de baix consum. A continuació, els capítols 3, 4 i 5 es centren en proporcionar solucions per optimitzar aspectes específics d'aquests conceptes. Més en detall, el capítol 3 estudia els principals reptes en el problema de la incrustació de VONs i presenta solucions que permetin assignar recursos de manera optimitzada a les VONs en un substrat físic. El capítol 4 proposa el concepte de l'Split Spectrum (SS) com una forma de millorar la utilització de l'espectre en les EONs. Finalment, el capítol 5 es centra en proporcionar i avaluar solucions arquitectòniques i d'enrutament amb l'objectiu de reduir el consum d'energia del substrat òptic de tal manera que VONs amb menor OPEX puguin ser desplegades a través d'ell.Los actuales propietarios de las redes de transporte se centran en ofrecer servicios mediante las infraestructuras que poseen y gestionan, mientras que los usuarios finales no tienen ningún control sobre estos. Tradicionalmente, este ha sido el modelo de negocio adoptado por los operadores de redes, ya que el coste de construir y mantener las infraestructuras correspondientes por tal de ofrecer servicios mediante ellas era, y aun es, considerablemente elevado. No obstante, el tráfico en Internet ha crecido de manera rápida y sostenida durante los últimos años y se prevé que continuara con este crecimiento en el futuro. Además, la aparición de nuevos servicios y paradigmas, están llevando al límite las actuales infraestructuras de telecomunicaciones, especialmente las redes de trasporte óptico. Por tal de superar dicha situación, la virtualización de redes ha sido considerada como una solución efectiva para las futuras arquitecturas de redes ópticas. Gracias a las Redes Ópticas Virtuales (VONs), es posible crear infraestructuras lógicas especificas en su misión, las cuales podrán satisfacer los requisitos de las aplicaciones que se ejecutaran a través de ellas, usando y compartiendo un único sustrato físico. No obstante, la aplicación de las técnicas de virtualización en el dominio óptico aun es sujeto de investigación, siendo el mapeo entre los recursos virtuales y los físicos (también conocido como incrustación de la red virtual) un punto clave a solucionar. No obstante, la virtualización por si misma no ofrece una solución suficientemente flexible en términos de utilización del ancho de banda. Por tal de proporcionar un entorno de virtualización suficientemente flexible para acomodar cualquier ancho de banda con suficiente granularidad, es necesario que el sustrato físico adopte una tecnología de transporte igual de flexible. Las Redes Ópticas Elásticas (EONs) se presentan como una solución eficiente para una asignación flexible del ancho de banda en redes ópticas. Además, debido a la heterogeneidad y dinamismo de los perfiles de tráfico a los cuales se enfrentaran las redes virtuales, es altamente deseable proporcionar una infraestructura física que ayuda a mantener bajos los gastos operativos (OPEX) de estas redes, siendo un parámetro muy importante el consumo energético asociado a la operación de las VONs. El tema del consumo energético ha sido, y aun es, sujeto de grandes iniciativas de investigación centradas en desarrollar nuevas arquitecturas de dispositivos o algoritmos de asignación de recursos conscientes del consumo energético por tal de proporcionar redes de transporte ópticas más eficientes energéticamente que, a su vez, permitan crear infraestructuras virtuales menos costosas des del punto de vista energético. Esta tesis se centra en el estudio de la composición y asignación de recursos a las VONs, con el objetivo de proporcionar un entorno flexible, eficiente y optimizado para la incrustación de las VONs en el sustrato físico real. El escenario considerado se compone de una red de transporte subyacente, ya sea una Red Óptica de Conmutación de Longitud de Onda (WSON) o EON, y múltiples VONs cliente, las cuales se colocaran encima del sustrato físico. En este escenario, un aspecto clave se refiere a como los recursos reales se asocian a los virtuales, garantizando el aislamiento entre VONs y satisfaciendo los recursos pedidos (por ejemplo, capacidad de enlace) por cada una de ellas. Después de una introducción a la tesis, el capítulo 2 revisa las infraestructuras de redes ópticas actuales, concluyendo en la necesidad de avanzar hacia una infraestructura de red óptica más dinámica y eficiente por tal de afrontar el crecimiento del tráfico en Internet y la aparición de nuevos servicios y paradigmas. Seguidamente, se procede a resumir el estado del arte de los conceptos y paradigmas que permitirán habilitar esta arquitectura de red, básicamente, VONs, EONs y las infraestructuras ópticas de bajo consumo energético. A continuación, los capítulos 3, 4 y 5 se centran en proporcionar soluciones para optimizar aspectos específicos de estos conceptos con la finalidad de proporcionar un marco optimizado que ayudara en la configuración de las futuras infraestructuras de redes ópticas y sus modelos de negocio. Concretamente, el capítulo 3 estudia los principales retos en el problema de la incrustación de VONs y presenta soluciones que permiten una asignación de recursos optimizada a las VONs en un sustrato físico dependiendo de las características de las VONs y del sustrato de red. El capítulo 4 propone el concepto de Split Spectrum (SS) como una forma de mejorar la utilizaci_on del espectro en las EONs. Finalmente, el capítulo 5 se centra en proporcionar y evaluar soluciones arquitectónicas y de enrutamiento con el objetivo de reducir el consumo energético del sustrato óptico de tal manera que VONs con menor OPEX puedan ser desplegadas mediante este sustrato

Alocação de recursos em redes ópticas elásticas baseadas em multiplexação por divisão espacial

Orientador: Nelson Luis Saldanha da FonsecaDissertação (mestrado) - Universidade Estadual de Campinas, Instituto de ComputaçãoResumo: Tecnologias de redes ópticas baseadas em fibras mono-núcleo e mono-modo possuem limite de capacidade e não conseguem suprir a demanda crescente de largura de banda. Um forma de resolver esse problema se dá através do uso de multiplexação por divisão espacial (SDM - \textit{Space-Division Multiplexing}). A transmissão de dados em SDM ocorre através de múltiplos núcleos agrupados em um único filamento de fibra, ou utilizando múltiplos modos transversais suportados por um núcleo. A combinação da flexibilidade de redes ópticas elásticas (EON - \textit{Elastic Optical Networks}) e a alta capacidade do SDM é promissora para o futuro das redes ópticas. Na camada de enlace, quando uma nova solicitação para estabelecimento de conexão chega, é necessário fazer a reserva de recursos para realizar essa conexão. A determinação dos recursos a serem alocados é dada pela solução do problema de roteamento, alocação de núcleo e \textit{slots} (RCSA - \textit{Routing, Core and Spectrum Allocation}). Na alocação de recursos, algumas restrições devem ser respeitadas, tais como a contiguidade e continuidade dos \textit{slots} de frequência, e tolerância ao \textit{crosstalk} espacial. Estas restrições implicam em uma maior complexidade para a acomodação do tráfego das conexões. A virtualização de redes permite que redes virtuais compartilhem recursos físicos, simplificando o gerenciamento de recursos na camada óptica, oferecendo flexibilidade na alocação de recursos e segurança dos serviços. Um dos principais desafios da virtualização é configurar de forma eficiente as redes virtuais, que consiste na alocação de recursos físicos para acomodá-las. Esta tese propõe soluções para o problema do RCSA em redes SDM-EON. A primeira contribuição desta tese é um algoritmo que considera o equilíbrio entre eficiência energética e bloqueio de requisições. Propõe-se um algoritmo de agregação de tráfego em lote, capitalizando na flexibilidade temporal para satisfazer requisições com o objetivo de formar lotes de requisições, aumentando assim a probabilidade de serem atendidas as requisições em um outro momento. A segunda contribuição desta tese é direcionada para a solução do problema da fragmentação, que ocorre em cenários onde pequenos conjuntos de \textit{slots} disponíveis ficam espalhados no espectro, causando o bloqueio de novas requisição. Propõem-se um conjunto de algoritmos proativos e reativos. Os algoritmos proativos utilizam diferentes técnicas, tais como, múltiplos caminhos, priorização de núcleo e área, bem como métricas de avaliação da fragmentação na composição de caminhos. O algoritmo reativo utiliza aprendizagem de máquina para fazer um rearranjo espectral e aumentar a capacidade de prevenção da fragmentação no RCSA. A terceira contribuição desta tese é uma solução para aumentar a eficiência do compartilhamento de recursos em redes virtuais. Este problema consiste na configuração de enlaces e nós virtuais para caminhos e nós físicos, respectivamente. A solução proposta introduz uma arquitetura utilizando aprendizado de máquina, que age como um assistente no processo de configuração de redes virtuaisAbstract: Optical network technologies based on a single-core and single-mode fibers have a limited capacity and cannot provide enough resources to a constant increase of bandwidth demands. One approach to overcome this is the use of Space-Division Multiplexing (SDM) which relies on sending data through multiple cores embedded into a single strand of fiber or using multiple transverse modes supported by a core. The combination of the flexibility of Elastic Optical Networks (EONs) and the high capacity of SDM is a promising solution to cope with the bandwidth demands. At the network level, when a traffic request arrives, it needs to reserve network resources to establish it. One approach to accommodate traffic demand over optical networks is the Routing, Core and Spectrum Allocation (RCSA), in which end-to-end lightpaths are offered for each individual request. In these scenarios, during the allocation process, some constraints need to be respected, such as contiguity and continuity of slots (selected in the resource selection process), and spatial crosstalk. These constraints pose extra complexity to accommodate the requests for the lightpath establishment. As one of the possible solutions, network virtualization is capable of improving the efficiency of optical networks, by allowing virtual networks to share the resources of physical networks, simplifying the management of resource and providing flexibility in resource allocation. One of the main challenges of network virtualization is to configure a virtual network efficiently which comprises allocating physical resources to accommodate incoming virtual networks. This thesis proposes solutions to the RCSA problem and the virtual network configuration problem for SDM-EON networks. The first contribution of this thesis is an algorithm to promote an equilibrium between reduction of the network energy consumption and reduction of the blocking of requests. For this purpose, we introduce a traffic grooming algorithm using batches, which takes advantage of the deadline of each request to form batches, increasing the chances of the requests to be established at another time. The second contribution of this thesis is a set of algorithms using different techniques to handle the fragmentation problem, where a small portion of available slot sequences end up scattered in a fiber link, blocking future requests, called the fragmentation problem. For this purpose, we propose proactive and reactive algorithms. Proactive algorithms use different techniques, such as multipath routing, core, and area prioritization, and metrics to use in the route selection process. The reactive algorithm uses machine learning to rearrange the spectrum and tune the RCSA algorithm to prevent the fragmentation. The third contribution of this thesis proposes a solution to improve resource sharing in network virtualization. This problem consists in configuring virtual links and nodes to physical nodes and paths. For this purpose, we propose a learning assistant control loop to handle the virtual network configuration problemMestradoCiência da ComputaçãoMestra em Ciência da Computação131025/2017-1CNP

Modeling and Analysis of Power Processing Systems (MAPPS). Volume 1: Technical report

Computer aided design and analysis techniques were applied to power processing equipment. Topics covered include: (1) discrete time domain analysis of switching regulators for performance analysis; (2) design optimization of power converters using augmented Lagrangian penalty function technique; (3) investigation of current-injected multiloop controlled switching regulators; and (4) application of optimization for Navy VSTOL energy power system. The generation of the mathematical models and the development and application of computer aided design techniques to solve the different mathematical models are discussed. Recommendations are made for future work that would enhance the application of the computer aided design techniques for power processing systems

Software Defined Applications in Cellular and Optical Networks

abstract: Small wireless cells have the potential to overcome bottlenecks in wireless access through the sharing of spectrum resources. A novel access backhaul network architecture based on a Smart Gateway (Sm-GW) between the small cell base stations, e.g., LTE eNBs, and the conventional backhaul gateways, e.g., LTE Servicing/Packet Gateways (S/P-GWs) has been introduced to address the bottleneck. The Sm-GW flexibly schedules uplink transmissions for the eNBs. Based on software defined networking (SDN) a management mechanism that allows multiple operator to flexibly inter-operate via multiple Sm-GWs with a multitude of small cells has been proposed. This dissertation also comprehensively survey the studies that examine the SDN paradigm in optical networks. Along with the PHY functional split improvements, the performance of Distributed Converged Cable Access Platform (DCCAP) in the cable architectures especially for the Remote-PHY and Remote-MACPHY nodes has been evaluated. In the PHY functional split, in addition to the re-use of infrastructure with a common FFT module for multiple technologies, a novel cross functional split interaction to cache the repetitive QAM symbols across time at the remote node to reduce the transmission rate requirement of the fronthaul link has been proposed.Dissertation/ThesisDoctoral Dissertation Electrical Engineering 201

Rôle clé de la Modélisation en Shape From Shading

National audienceLe problème du "Shape From Shading" (SFS) consiste à reconstruire la forme tri-dimensionnelle d'une surface à partir d'une unique image noir et blanc de cette surface. Le "Shape From Shading" est connu comme étant un problème mal posé. Dans cet article, nous montrons que si nous modélisons le problème de manière différente de celle qui est habituellement proposée (plus précisément en prenant en compte l'atténuation de l?éclairage due à la distance), le "Shape From Shading" devient complètement bien posé. Ainsi l'information d'ombrage permet, à elle seule, de reconstruire (presque) n'importe quelle surface à partir d'une unique image (de cette surface). Aucune donnée additionnelle telle que la hauteur de la solution aux "minima" locaux (contrairement à [7, 28, 12, 31, 15]) et aucune hypothèse de régularité (contrairement à [20, 13], par exemple) ne sont nécessaires. Plus précisément, nous reformulons le problème sous la forme d?une nouvelle Equation aux Dérivées Partielles (EDP), nous développons une étude mathématique complète de cette équation, enfin nous proposons une nouvelle méthode numérique permettant de résoudre cette équation. Par ailleurs, nous prouvons la convergence de notre méthode. Nous démontrons aussi expérimentalement la pertinence de notre nouvelle méthode en l'appliquant avec succès à diverses images synthétiques et réelles

Study, evaluation and contributions to new algorithms for the embedding problem in a network virtualization environment

Network virtualization is recognized as an enabling technology for the future Internet. It aims to overcome the resistance of the current Internet to architectural change and to enable a new business model decoupling the network services from the underlying infrastructure. The problem of embedding virtual networks in a substrate network is the main resource allocation challenge in network virtualization and is usually referred to as the Virtual Network Embedding (VNE) problem. VNE deals with the allocation of virtual resources both in nodes and links. Therefore, it can be divided into two sub-problems: Virtual Node Mapping where virtual nodes have to be allocated in physical nodes and Virtual Link Mapping where virtual links connecting these virtual nodes have to be mapped to paths connecting the corresponding nodes in the substrate network. Application of network virtualization relies on algorithms that can instantiate virtualized networks on a substrate infrastructure, optimizing the layout for service-relevant metrics. This class of algorithms is commonly known as VNE algorithms. This thesis proposes a set of contributions to solve the research challenges of the VNE that have not been tackled by the research community. To do that, it performs a deep and comprehensive survey of virtual network embedding. The first research challenge identified is the lack of proposals to solve the virtual link mapping stage of VNE using single path in the physical network. As this problem is NP-hard, existing proposals solve it using well known shortest path algorithms that limit the mapping considering just one constraint. This thesis proposes the use of a mathematical multi-constraint routing framework called paths algebra to solve the virtual link mapping stage. Besides, the thesis introduces a new demand caused by virtual link demands into physical nodes acting as intermediate (hidden) hops in a path of the physical network. Most of the current VNE approaches are centralized. They suffer of scalability issues and provide a single point of failure. In addition, they are not able to embed virtual network requests arriving at the same time in parallel. To solve this challenge, this thesis proposes a distributed, parallel and universal virtual network embedding framework. The proposed framework can be used to run any existing embedding algorithm in a distributed way. Thereby, computational load for embedding multiple virtual networks is spread across the substrate network Energy efficiency is one of the main challenges in future networking environments. Network virtualization can be used to tackle this problem by sharing hardware, instead of requiring dedicated hardware for each instance. Until now, VNE algorithms do not consider energy as a factor for the mapping. This thesis introduces the energy aware VNE where the main objective is to switch off as many network nodes and interfaces as possible by allocating the virtual demands to a consolidated subset of active physical networking equipment. To evaluate and validate the aforementioned VNE proposals, this thesis helped in the development of a software framework called ALgorithms for Embedding VIrtual Networks (ALEVIN). ALEVIN allows to easily implement, evaluate and compare different VNE algorithms according to a set of metrics, which evaluate the algorithms and compute their results on a given scenario for arbitrary parameters